Inclusion Criteria:

• ≥ 18 to ≤ 80 years (at date of signing ICF).
• Urine protein to creatinine ratio (UPCR) of ≥ 3.0 g/g (as measured from a 24 hour urine collection).
• Active and anti-PLA2R antibody positive MN in need for IST according to investigator judgement and diagnosed on the basis of a biopsy, archival biopsy acquired within 5 years prior to screening is acceptable.
• Estimated glomerular filtration rate (eGFR) ≥ 50 ml/min/1.73m² or >30 and < 50 ml/min/1.73m², and IFTA (interstitial fibrosis and tubular atrophy) score of less than 25% on a renal biopsy obtained within the last 6 months prior to start of screening. If a subject falls into the latter range without availability of an adequate biopsy, a biopsy at screening should be performed for IFTA assessment.
• The subject is on supportive treatment with an ACEI or an ARB for at least 4 weeks prior to screening. The ACEI or ARB treatment should have reached a stable dose according to best local practice.
• Systolic BP ≤ 150 mmHg and diastolic BP ≤ 100 mmHg after a period of 5 minutes of rest as measured at screening.
• Subject vaccinated against Pneumococcus within the last 3 years prior to date of signing ICF (subjects may be vaccinated during screening to meet this criterion; interval to first dose of MOR202 must be at least 14 days (1)).
• Cohort 1a (newly diagnosed patients):
  • Serum anti-PLA2R antibodies ≥ 150.0 RU/mL determined at screening by Euroimmun ELISA.
• Cohort 1b (relapse subjects):
  • Must have had complete immunological and/or clinical remission lasting for at least 6 months according to clinical judgement and serum anti-PLA2R antibodies ≥ 50.0 RU/mL determined at screening by Euroimmun ELISA.
• Cohort 2:
  • Failure of immediate previous therapy; i.e. subject never achieved a complete immunological and/or clinical remission according to clinical judgement during or after completion of a recognized IST containing CSA, tacrolimus, MMF, ACTH or alkylating agents (e.g., cyclophosphamide), or RTX determined after at least 6 months after start of this IST. Serum anti-PLA2R antibodies ≥ 20.0 RU/mL measured at screening by the Euroimmun ELISA. 11.
• Cohort 2:
  • Subjects may have received a maximum of two prior treatment lines of immunosuppressive therapy (retreatment for relapse with the same regimen is considered a line of its own). A planned, fixed sequence of different therapeutic agents (e.g., STARMEN(2) regimen) is considered as one regimen.
• Note: France will only enroll patients in Cohort 2. Parameters in italics are measured in a central laboratory.

Exclusion Criteria:

• Hemoglobin < 90 g/L;
• Thrombocytopenia:
  • Platelets < 100.0 x 10^9 /L;
• Neutropenia:
  • Neutrophils < 1.5 x 10^9 /L.
• Leukopenia:
  • Leukocytes <3.0 x 10^9 /L.
• Hypogammaglobulinemia:
  • Serum immunoglobulins ≤ 5.0 g/L.
• Secondary cause of MN (e.g., SLE, medications, malignancies) as determined by the investigator.
• Concomitant renal disease other than MN (e.g., diabetic renal disease, lupus nephritis, IgA nephropathy).